Telephone system



Sept. 5, 1933. M. LANGER l-:r Al.

TELEPHONE SYSTEM Filed Feb. 19, 1932 2 Sheets-Sheet 1 il--- g l1 3 95S nEm x N ka. \w N S u *.gm l l @i S. E H m. L rl uw w. N 1 9G.. .4% .RR EJ WNNV.. N bbw Il.-. vx. Nv. .lli w; hay m3 u www.. -i .NRQW .nxhak/ RNWtw" W` Nth J .3% J ---1. NG .\.l .5. L RQ NmN N TELEPHONE SYS TEM FiledFeb, 19, 19252 2 Sheets-Sheet 2 Patented Sept. 5, 1933 UNITED STATESPATENT OFFICE TELEPHONE SYSTEM Application February 19, 1932. Serial No.594,086 and in Germany February 20, 1931 12 Claims.

The invention relates to telephone systems in which lines, reached overfree hunting switches, may be reached by additional free huntingswitches. In such systems, when a line, reached 3 over a free huntingswitch, is taken into use, it is essential to make this lineinaccessible to the other switches. This, according to the invention, isachieved by switching means which make this line inaccessible to theremaining free hunting 30 switches only when a station, connected to thereached line, dials.

An unnecessarily lengthy seizure of the junction lines, reached overfree hunting switches, is prevented by means of the arrangement ac- 15cording to the invention with the result that, due to the shorter periodduring which the junction lines are engaged, the total number ofjunction lines to be erected for a. telephone system is reduced. Thisresults in greater economy in the system, although its operation isequally reliable.

This switching arrangement is particularly advantageous in exchangeshaving a plurality of traffic directions, especially in systems in whichseveral impulse receivers are simultaneously set by the calling station,as the line selection of the distant exchange is carried out overswitches of the above mentioned type. The greatest advantage gained bythe invention is to be found in a very much greater utilization of thejunction lines connecting the exchanges.

An embodiment of the invention is shown in Figs. l, 2, and 3, but theinvention, however, is not limited to this embodiment only. Fig. 1 is ageneral plan. Tnl and Tn2 represent two subscribers stations which haveaccess to the rst group selectors (IGWI, IGWZ) in their exchangeN A overtheir preselectors VWl and VW2. Each first group selector is associatedwith a preselecting secondary lineswitch. The lineswitches MWl and MW2have both been set to the same line L1 leading to a group selector IGW3in the exchange B. It will now be assumed, as an example, that thelevels 1 5, in the Vgroup selector, are reserved for traffic theexchange A, and the identification digits 6--0 for trac with theexchange B. Conversations within the exchange A are guardedA by the rstline loop breaking, for example, for Tnl the lin-e L1, to which thelineswitch associated with the group selector IGWl, in this case forexample MWl, has been set, the other lineswitch, for example, MWZ, whichis connected to the same line in the meantime having been set tothesucceeding free line, for example, L2. The group selector IGWl inexchange A, and the group selector IGWZi in exchange B, are operatedsimultaneously upon dialling, the group selector IGW3 in exchange Bbeing released when the identification digit of the exchange is dialled,releasing the line L1 at the same time. Connections are completed in 50the same manner for conversations with the eicchange B, although in thiscase the group selector IGWl in exchange A is not released. It should bementioned in this connection that devices are provided, which, whenimpulses are transmitted a5 over still operating free hunting switchesor over a switch still' guarding a line, prevent the setting up of aconnection over such a switch. l The inanner in which a connection iscompleted will be described below in conjunction with Figs. 2 and 70 3of the drawings.

The circuits for completing the connection in dicated in Fig. l areclearly shown in Figs. 2 and 3. Only the wipers of the preselectors VWIand VW2 are shown in these gures. The test cir- 75 cuit in the groupselector IGW2, for the preselector VS2, and the circuits for the settingof the switch, have not been illustrated" in Fig. 8, since they areexactly the same as those in the group selector IGWl, shown in Fig. 2.

If, for example, the subscriber Tnl wishes to set up a connection to hisown exchange' A, the following switching operations take place: Thelifting of the receiver at Tnl causes the associated preselector VWl tohunt for a line leading to a free group selector, for example, the groupselector IG'WI. When this group selector IGWl is seized, windings I ofrelays A and B are energized ove'i earth, battery, relay A, line L3,subscribers line loop, line' L4, relay B, earth. QQ By means of contact3b, relay B removes the' short circuit4 for relay C so' that this isenergized over: earth, windings IIY of relays A and B`, contacts 21e,lo. relay C, line L5, battery, earth in the preselector Relay Cactuat'es its contacts 95 4c, 5c, 9c, 30C, 34o. Relay X is energizedover contact V4c and actuates its contacts 14.1: and 391e. Relay() ismaintained energized over coritact 5c until released. Earth ispreparatrily applied, at contact 30e, tothe impulse line leading to ex-100 change B, over the. lineswitch MWI. When contacts 8a, V19e :areactuated, Winding III of relay V is energized over:V earth, contacts 6p,7k, winding of relay if, contacts 8a, 9c, 10a, w, vertical magnet H,battery, earth. The current in this circuit being too wealg, thevertical magnet is unable t o operate. The exchangehsignal AZisfconnected up by contact lo inthe following circuit: earth, condenserC13, repeater Winding of AZ, contacts 142, 2k. windings II of relays B110" .,eiected in the same manner.

and A, earth. The secondary line-switch MWI, associated with the groupselector IGWI, is of the preselecting type. Therefore, it has selected afree junction line leading to the exchange B.

The setting of the secondary lineswitch to a. free line takes place asfollows:

In an unoperated condition relay P1 is at normal and the rotary magnetD1 is connected to battery over: earth, battery, rotary magnet Dl,contacts lipl, d1, 121 earth. When the secondary lineswitch MWl findsarfree line, for example, the line LlG---Ll3, winding I of relay P1 isenergized over: earth, relay P1, winding I line L13, battery in thegroup selector IGW3 (not shown), earth. By means of contact 11121, relayP1 opens the rotary magnet circuit, causing the switch to be brought torest. The test circuit over line L12 is prepared by contact lpl. It isassumed, in the present example, that not only the secondary lineswitchMWI but also the lineswtch MW2, which is associated with the groupselector IGW2, has been set to the lines L10-L13. The setting of thesetwo secondary lineswitches is Relay P', of the secondary lineswitch MWZ,is connected to the line L13 over line L20 and is energized in parallelwith relay Pl of the secondary lineswitch MWI. In Figs. 2 and 3 thesecondary lineswitches MWl and MW2 are shown in a set condition, that isto say, their test relays P1 and P1' have been energized. The normalpositions of their contacts are indicated by dotted lines.

The subscriber V'Inl may now commence dialling. The identiiicationdigits 1-5 being allocated to the traffic with the exchange A, he dials,for example, the digit 5. Relay A, during the dialling, releases inaccordance with the line loop interruptions, whereas relay B, in theform of a i slow acting relay, remains energized during the ergizedduring the impulse series.

impulse output. The Vertical magnet H is intermittently energized over:earth, contacts 8a., 9c. winding II of relay V, contacts 33d, w,vertical magnet H, battery, earth. Relay V remains en- The oli-normalcontacts 2k and "Ik: are tluown over at the first vertical step. Theexchange signal is disconnected by contact 2k, whereas contact '7kprepares the circuit for the rotary magnet. Re-

. lay V releases with slow action after the end of the impulse seriesand closes the circuit for the rotary magnet D, which is energized inthe following circuit: earth, contacts 6p, 7k, 32o, rotary magnet D,battery, earth. The magnet operates, thereby actuating itscontact 33d.This causes relay V to be energized afresh over earth, contact 33d,winding I of relay V, vertical magnet H, earth. By means of its contact32o, relay V opens the circuit for the rotary magnet D, which thereuponis released, causing its Contact 33d to be re-opencd. This disconnectsrelay V which closes its contact 32o with the result that the rotarymagnet D is reenergized, causing the switch to execute a further step.This interaction continues until the switch encounters a free line.

VThe circuit for relay P2 is closed by contact 16a at the rst release ofrelay A. Relay P2 is then energized over: earth, contacts 13p, 14x,15171, 16a, re lay P2, contact 17g, line L12, to the group selector IGW3in exchange B, battery, earth (not shown), and remains energized overits contact 18102. Rclay P2, by means of its contact 20192, appliesearth to the line L13, with the result that winding I of relay P1 isshort-circuited. Winding II of relay P1, however, is connected up bycontact 19112, thus preventing this relay from being' deenergized. Earthhaving been applied to the line L13, and consequently also line L20, al1the test relays of the secondary line switches which had been set to thesame line leading to exchange B are short-circuited. Relay P1', in thepresent embodiment, is released, thereby closing its contact 31101'.Battery is thereby applied to the rotary magnet D1', and the secondarylineswitch MW2 continues to hunt until it encounters a free line. Thelines L10 and L11, leading to exchange B, are switched through to thegroup selector IGWl by contacts 21102 and 22112. The closing of contact21:02 causes earth to be applied over contacts 3Go and 23a to the lineL10 which leads to exchange B. The line loop interruptions, set up whensubscriber Tnl dials, are thus transmitted to exchange B over contact23a, the group selector IGWl in exchange A as Well as the group selectorIGWB in exchange B being set in accordance with the said line loopinterruptions. Relay P is energized in the following circuit when thefree line L-LS is connected up: earth, contacts 30e, 23a, relay P, wipercgwl, line L8, battery, earth in the succeeding switch (not shown). Re-

lay P short circuits its high resistance winding II Il.

and remains energized over its contact 35p. The lines L3 and L4 areswitched through to the lines L6 and L7, by means'of contacts 24p and36p. The opening of contact 13p opens the circuit for relay P2, causingthis relay to release. This disdenoting the traffic with the exchange B,the seizif I ing and setting of the group selectors IGWi and IGW3 takesplace in the same manner. In the levels reserved for traiiic withexchange B, however, the lines L6 and L7 are not to be found. Battery isapplied to the first level contact of the switch wiper cgwl over contact37g, with the result that, when the switch is operated to this level,relay P will be energized over: earth, battery, contact 371/, line L9,wiper cgwl, windings I and II of relay P, contacts 23a, 30o, earth.Relay P remains energized over contact'ip and opens contact 13p. At thesame time, however, contact rk' is closed when the switch operates, withthe consequence that the circuit for relay P2 is not out oi. Thesubscriber Tnl, therefore, switched through to the exchange B overcontacts 24p, 36p, 21192, and 22102 and the lines L10 and L11.

Should it occur that two subscribers T'rLI and T112 start dialling atexactly the same time, it being assumed that Vthe secondary lineswitchesMWI and MWZ allocated to their respective first group selectors IGWl andIGWZ have been set to the same outgoing line L10-L13, devices will haveto be provided, which, upon transmisl sion of impulses over a secondarylineswitch, set to a guarded line, or Yover still operatinglineswitches, prevent the setting up of a connection over such a switch.:The subscriber T112 is connected to the group selector IGW2 over hispreiso its contacts, .applying earth to` the lines Lm and L12 by means.of contact 47112'. This causes relay P1, which ts associated with thegroup iselector IGWl and line L13, to be short-cimmed, with the resultthat it releases. Voltage is applied tothe rotary magnet of thesecondary lineswitch MWI over: earth, battery, rotary magnet Dl,contacts lipl, d1, 12:41, earth, so that the lineswttch is advanced. Butthe mascriber Tm started dialling at the same time as subscriber T112.When battery is out oit Ifor the first time trom the line relay A,allocated to the subscriber T111, the secondary lineswitch'MWi has notyet encountered a free line leading to Vexchange B, with the result thatcontact 503:1, therefore, is still closed. Relay Y is then energiaedover: earth, battery, relay Y, contacts 51ml, 38a, 39x, earth, remainingenergized over its contact 51g. At contact 12g, relay Y breaks thecircuit for the rotary magnet, of the secondary lineswiteh, preventingthis from operating, and opens contact 37g to the line L9. Il' thesubscriber Tnl wishes to get into communication with the exchange A, theswitch is set to the level which corresponds to the selected digit andhunts freely until it nds a free line. The operations in conjunctiontherewith have already been described. But if this subscriber Tnlrequires exchange B, the group selector IGWl will receive no potentialwhen encountering the selected level as Contact 37g has been opened. Theswitch, therefore, is set to the eleventh step, whereupon relay P willbe energized over: earth, battery, relay A, Winding III, rotaryoff-normal contact 52w11, relay P, contacts 23a, 30e, earth. Relay P isenergized and brings the switch to rest by opening its contact 6p.Contact 1711; was opened, upon the energization of relay Y, thus openingthe circuit for relay P2 Which consequently released. Relay P2 openedits contacts 22122 and 21p2, which prevented transmission of impulsesover contact 23a for the setting of the switch in exchange B, succeedingthe secondary lineswitch MWI. Therefore, the group selector IGW3 inexchange B does not receive impulses from two different group selectors,for example, IGWl and IGW2, when the associated secondary lineswitchesMWI and MW2 have been set to the same line leading to the group selectorIGWB and two subscribers start dialling at exactly the same time. Thebusy signal is transmitted to the subscriber Tnl over contact 5311111,indicating that the connection cannot be set up, and that he will haveto make the attempt later. The setting of the succeeding switches, aswell as the release at the end of the conversation, takes place in knownmanner. When the subscriber Tnl hangs up his receiver, relays A and Bare deenergized and released. Relay C is shortcircuited by contact 3b,causing this relay to open its contacts. Contact 34e short-circuitsrelay P, which in turn causes the switches, which succeed the groupselector IGWl, to be released.

What is claimed is:

l. In an automatic telephone system, a selector repeater and anassociated lineswitch in a local exchange, a trunk line extending to aselector in a distant exchange accessible to said linesWitch, meansresponsive only when a calling subscriber starts to dial for marking thetrunk line to the distant exchange busy to all other lineswitches havingaccess thereto, and means responsive to the digit dialled forsimultaneously setting said selectorV repeater and said selector intimidi-starrt exchange.

' 2; In'an automatic telephone system, a selector repeater' and anassociated lineswitch in a local exchange, a trunk line extending to aselector in aV distant exchange accessible to said linesw'ltch, meansresponsive only 'when a calling subscriber starts to dial for markingthe trunk line to the distant exchange busy to all other lineswitcheshaving access thereto, means responsive to the digit halted forsimultaneously setting said selecter'repetr and said selector in thedistant exchange, and means responsive when the digit dialled determinesthat the call is not for a. subscribes'Y in said distant exchange forremoving the busy marking from said trunk and for releasing the selectoroperated thereover.

In an automatic telephone system, a selector repeater and an associatedlineswitch in a local exchange, a trunk line extending to a selectorinria distant exchange accessible vto said lineswitch, means responsiveonly when a calling subscriber starts to dial for marking the trunk lineto distant exchange busy to all other linesv'vitcheshaving accessthereto, means responsive teYV Ythe digit dialled for simultaneouslysetting said selector repeater and said selector in the distantexchange, and means responsive when the call is for a subscriber in saiddistant exchange for maintaining said selector repeater and associatedlineswitch in an operated position and for repeating the impulses of theremaining digits of the wanted subscribers number over said trunk lineto set the remaining switches in the distant exchange to complete thecall.

4. In an automatic telephone system, a selector repeater for use in abranch exchange, a preselecting lineswitch associated with said selectorrepeater for selecting a trunk to a main exchange Without making theselected trunk busy, and means responsive when a calling subscriberstarts to dial for marking the selected trunk line busy.

5. In an automatic telephone system, a selector repeater for use in abranch exchange, a preselecting lineswitch associated with said selectorrepeater for selecting a trunk to a main exchange without making theselected trunk busy, means responsive When a calling subscriber startsto dial for marking the selected trunk line busy, and means for removingthe busy condition from the main exchange trunk when the value of thedigit dialled determines that the call is for a branch exchangesubscriber.

6. In an automatic telephone system, a trunk line extending to aselector repeater, a preselecting lineswitch associated with saidselector repeater, a trunk line extending to a selector in a distantexchange preselected by said lineswitch, means at a calling subscribersstation for transmitting impulses to simultaneously set said selectorrepeater and said selector, and means responsive only when saidsubscriber starts to transmit impulses for marking the trunk line to thedistant exchange busy to all other preselecting lineswitches that areconnected or that have access thereto.

7. In an automatic telephone system, a trunk line extending to aselector repeater, a preselecting lineswitch associated With saidselector repeater, a trunk line extending to a selector in a distantexchange preselected by said lineswitch, means at a calling subscribersstation for transmitting impulses to simultaneously set said selectorrepeater and said selector, means responsive only when said subscriberstarts to transmit impulses for marking the trunk line to the distantexchange busy to all other preselecting lineswitches that are connectedor that have access thereto, said preselecting lineswitches arranged toautomatically rotate to select an idle trunk when said busy marking isencountered.

8. In an automatic telephone system, a trunk line extending to aselector repeater, a preselecting lineswitch associated with saidselector repeater, a trunk line extending to a selector in a distantexchange preselected by said lineswitch, means at a calling subscribersstation for transmitting impulses to simultaneously set said selectorrepeater and said selector, means responsive only when said subscriberstarts to transmit impulses for marking the trunk line to the distantexchange busy to all other preselecting lineswitches that are connectedor that have access thereto, and means for preventing the setting of theselector in said distant exchange when impulses are transmitted over ahunting lineswitch.

9. In a system as claimed in claim 8 in which means are provided fordisconnecting the conductor over which impulses are transmitted to setthe selector in said distant exchange to prevent the setting up of aconnection.

10. In a system as set forth in claim 8 in which means are provided forgiving the calling subscriber a busy signal when the connection to thedistant exchange is prevented.

11. In an automatic telephone system, a trunk line accessible to callingsubscribers, a repeater in said trunk line, a lineswitch for extendingthe trunk line responsive to a call, there being a plurality of othertrunk lines accessible t0 said lineswitch which may be used, means insaid repeater for transmitting impulses over the trunk extension, andmeans responsive to the initation of the impulse transmission for makingthe other trunk line involved busy.

12. In an automatic telephone system, a group of trunk lines, a secondtrunk line, means responsive to a call for linking a connection througha trunk line of said group and said second trunk line, means fortransmitting impulses over the linked connection. and means responsiveto the initiation of impulse transmission for making said second trunkline busy.

MAX LANGER. ALFRED SCHEUNERT. KURT WOLLACK.

